A variety of different configurations have been proposed for the conventional thermo valve.
For example, a thermo valve used in a cooling device for lubricant and cooling oil in the vehicle transmission is disclosed in Patent Document 1. Briefly, a movable thermo-element is disposed inside a case that constitutes the thermo valve; as the thermo-element moves, it opens and closes a flow path using a flow path closing member that is a main valve attached to the thermo-element.
In the above-described thermo valve, when the oil exceeds a certain temperature, oil flowing out of the vehicle transmission is passed through an oil cooler and returned to the vehicle transmission, and when the oil falls to a certain temperature the oil cooler circuit is bypassed and the flow of oil returned to the vehicle transmission is controlled by the opening and closing of the main valve that is the flow path closing member that controls the flow of oil returned to the vehicle transmission. In the event that that oil that flows directly from the vehicle transmission to the oil cooler achieves a certain pressure, a flow path closing member that is a bypass valve and which is separate from the flow path closing member that is the main valve operates and releases the pressure.
A thermo valve similar to that described above is disclosed in Patent Document 2. That is, in this conventional example, unlike the thermo valve of Patent Document 1 described above, this thermo valve eliminates the flow path closing member that is the main valve and uses the thermo-element itself as the main valve, with the thermo-element biased by a coil spring.